Daniella Ferraro Fernandes Costa Pinho MD, Abstract Co-Author: Nothing to Disclose

Adriano Tachibana MD, Abstract Co-Author: Nothing to Disclose

Caroline Duarte de Mello Amoedo MD, Presenter: Nothing to Disclose

Fernanda Marques Abatepaulo, Abstract Co-Author: Nothing to Disclose

Ronaldo Hueb Baroni MD, Abstract Co-Author: Nothing to Disclose

Marcelo B. Funari MD, Abstract Co-Author: Nothing to Disclose

To assess radiation dose reduction for abdominal multidetector computed tomography (MDCT) examinations with the adaptive iterative dose reduction (AIDR) technique.

In this ongoing study, we retrospectively evaluated 36 patients with a prior contrast enhanced abdominal MDCT with filtered back projection (FBP), and a subsequent follow-up study using AIDR reconstruction (Aquillion ONE, Toshiba). The abdominal MDCTs with AIDR were performed during the venous phase using a collimation of 80 x 0.5 mm, 0.5s rotation time, pitch of 0.813, 120 kVp, modulated mA using a standard deviation of noise of 11.5, and reconstruction with standard AIDR 3D. The control group (same patients with a previous exam using FBP) was scanned using a collimation of 160 x 0.5 mm and pitch of 0.869 (or 64 x 0.5 mm and pitch of 0.828), 120 kVp and modulated mA using a standard deviation of noise of 12.5, with FBP reconstruction. CT dose index volume (CTDIvol), dose length product (DLP) and effective dose were recorded. Two blinded readers rated image quality, image noise and sharpness on 5-point-scales, and also the overall acceptance of images. The aorto-iliac and hepatic attenuation, signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were recorded. Statistical analyses were performed by paired t-test and Wilcoxon test.

AIDR allowed for an overall average decrease of 63% in CTDIvol (AIDR, 10±5.2; FBP 27±9.3 mGy) (p < 0.0001), and 50% decrease in DLP and effective dose (AIDR 548.6±346.1 mGy-cm and 8.2±5.2 mSv; FBP 1105.4±622 mGy-cm and 16.6±9.3 mSv, respectively) (p < 0.0001). Image quality, sharpness, image noise, SNR, CNR and attenuation were similar in both groups (p>0.3). The objective noise was also comparable (p=0.53). All images from both groups were rated as acceptable.

The AIDR technique allows substantial radiation dose reduction for abdominal CT examinations with similar image quality compared with FBP technique.

Substantial dose reduction is possible with the AIDR technique for abdominal MDCT, without compromising image quality.

Pinho, D, Tachibana, A, Amoedo, C, Abatepaulo, F, Baroni, R, Funari, M, Reducing MDCT Radiation Dose with Adaptive Iterative Dose Reduction (AIDR): Comparative Evaluation on Abdominal Exams.  Radiological Society of North America 2012 Scientific Assembly and Annual Meeting, November 25 - November 30, 2012 ,Chicago IL. http://archive.rsna.org/2012/12025339.html